UNRAVELLING THE ROLE OF RESIDUAL STRESS DISTRIBUTION IN THE PERFORMANCE OF BILAYERED ZIRCONIA RESTORATIONS – A NARRATIVE REVIEW Bilayered zirconia restorations have gained significant popularity in modern dentistry due to their ability to combine the strength of zirconia with the natural aesthetics provided by porcelain veneers. However, the longevity and performance of these restorations can be influenced by the distribution of residual stresses within the material. This narrative review aims to explore the impact of residual stress distribution on the longevity of bilayered zirconia restorations, focusing on factors affecting stress levels, and potential failure modes and mechanisms. A Boolean search of the PubMed database was done which yielded 40 articles, of which 26 articles were included in this review. The narrative review begins with an introduction to bilayered zirconia restorations, highlighting their composition and advantages in dental applications as well as the different veneering techniques used. Subsequently, the analysis delves into stress distribution within the restoration, emphasizing its importance in determining the restoration's mechanical behaviour. Factors influencing residual stress in bilayered zirconia are explored, material properties, sintering parameters and veneering methods. Understanding these factors is crucial for optimizing stress management during restoration fabrication. In light of the influence of residual stress on restoration durability, mitigation strategies for reducing stress levels are discussed.

EXPLORING THE USES, STERILIZATION AND STORAGE PROTOCOLS OF EXTRACTED HUMAN TEETH FOR RESEARCH ADVANCEMENTS: A SCOPING REVIEW Extracted human teeth (EHT) have long served as invaluable specimens in dental research, offering valuable insights into dental science and biomaterials. This scoping review aims to document the current uses of EHT in dental research and to identify the sterilisation and storage protocols. The study employed scoping review methods. Relevant databases (PubMed, Scopus, and Science Direct) were searched using the terms “extracted human teeth” and “in-vitro” to identify articles for inclusion. The most recent articles published over five years (2019-2023) and those in English were included. Two reviewers independently conducted the selection process, and the decision was consensually made. A descriptive statistical assessment was performed to analyse the studies involving EHT and the sterilising and storage solutions used. A total of 105 articles were reviewed: Endodontology (32%), Dental Materials (24%), Conservative Dentistry (20%), Prosthodontics (8%), Regenerative Therapy (6%), Oral Biology (5%), Orthodontics (4%), and Periodontology (3%). 71% of the reviewed papers did not report the sterilising and storage methods for EHT. When reported, sodium hypochlorite was most commonly used (15%). However, the concentrations and immersion time in the sterilising solutions were inconsistent. The most frequently used storage solutions to keep EHT from dehydration are saline (11%) and distilled water (10%). In conclusion, extracted human teeth continue to be extensively utilised in dental research. Nonetheless, the reporting and standardisation of sterilisation and storage methods are notably inadequate. A standardised guideline for sterilising and preserving extracted human teeth for various types of research is essential to mitigate variability and promote result uniformity. There is a stark absence of consensus regarding the optimal procedures for storing and sterilising EHT, even when used for the same laboratory investigations and different types of dental research.